Attachment for over-lock stitch sewing machine



ATTACHMENT FOR OVER-LOCK STITCH SEWING MACHINE Filed May 28, 1958 E. H.CONRAD Feb; 16, 1960 2 Sheets-Sheet 1 INVENTOR.

HIIHI Hmm LV/vve/ fame/10 CONRAD ATTACHMENT FOR OVER-LOCK STITCH SEWINGMACHINE Filed May 28, 1958 2 Sheet s 2 FIG.3

""HWHI! United States Patent ATTACHMENT FOR OVER-LOCK snrc SEWINGMACHINE Erich Henry Conrad, Teaueck, NJ.

Application May 28, 1958, Serial No. 738,369

14 Claims. (Cl. 112-254) The present invention relates to a sewingmachine and, more specifically, to such sewing machine in which aplurality of threads are fed to or in the direction of the needle fromdifferent sides of the machine, as is the case with an overlock-stitchmachine, such as the Merrow overlook stitching machine; and is directedto the provision of means associated with or attached to such machine bywhich the several thread-tensioning devices for the several differentthreads may be simultaneously loosened, to permit the free and easydrawing out of the several threads from the machine, for the purpose ofconvenient severance, between the several successive pieces of workproduced on the machine.

In sewing machines of the character to which the present inventionrelates, particularly overlock-stitch machines, a plurality of threadsare fed to or towards the needle from at least two sides, namely, thefront and a side of the head of the machine. Each of these threads istensioned, on its way to the needle, by individual tensioning means,generally consisting of a pair of discs, at least one of which isspring-tensioned against the other, between which discs a thread passes.When the stitching or sewing done on such machine is longitudinal inchar acter, so that successive pieces of work are linearly disposedrelative to one another, the problem of severing the pieces of work fromone another is relatively minor, be-

cause, since these successive pieces of work are linearly disposed, theymay be continuously processed with intervening blank stitches, in acontinuous row, and may be severed from one another at any time after arow of work pieces is completed. However, when the stitching done on themachine is non-linear, as when it comprises, for example, an overlockstitched hem on a circular item, when successive pieces of work do notfollow one another in a straight row, but curve back on the work tableof the machine, to interfere with the operators work, it is necessary toprovide long spacing sections of thread between the several pieces ofwork to permit them to move away in a linear direction from the machine,or to sever them conveniently and promptly as they are completed.Heretofore the provision of such long pieces of thread between pieces ofwork could not be easily. effected because it could be done only by theblank running of the machine for a relatively prolonged period of timebetween the completion of one piece of work and the insertion of thenext, or by the manual pulling of the threads. Blank running of themachine is time-wasting. Since the threads are multiple, come fromdifferent directions, and each of them is individually tensioned, theirpulling is physically very difiicult and also requires a substantialinterval of time.

The object of the present invention is to provide means, in associationwith a sewing machine of the character described, for relieving thetension on the threads, to permit their easy drawing out to thereby makethe provision of spacing thread sections between the work physicallyeasier and more rapid.

It is also an object of the. present invention to provide,

Patented Feb. 16, 196Q in association with the machine described, meansfor relieving the tension on each of the threads fed through the machinesimultaneously, by a single movement of the operators hand, to therebyfurther facilitate and speed the operation of the machine.

It is another object of the present invention to providethread-tension-releasing means for sewing machines of the characterdescribed comprising a single device or unit which may be in the form ofan attachment that can be secured in place upon any already existingsewing machine.

It is a further object of the present invention to providethread-tension-releasing means or device for sewing machines ofthe-character described which are of relatively simple construction;which may be economically produced and relatively quickly and easilyinstalled; which are simple, easy and convenient to operate and arehighly effective and eflicient for their purposes.

The foregoing and other objects and advantages of thethread-tension-releasing device of the present invention will becomemore readily apparent to those skilled in the art from the embodimentthereof shown in the accompanying drawing, in association with anoverlock stitch sewing machine, and from the description following. Itis to be understood, however, that such embodiment is shown by way ofillustration only, to make the principle and practice of the inventionmore readily comprehensible, and without any intent of limiting theinvention to the specific details therein shown.

In the drawings:

Fig. 1 is a top plan view of thehead of an overlockstitch sewing machinewith a thread-tension-releasing device of the present invention securedthereon and shown in operating position; and partly broken away todisclose structural details; p

Fig. 2 is a front elevational view of the same, with thethread-tension-releasing device shown in. normal, nonoperating position;

Fig. 3 is an end elevation of the sewing machine head shown in Fig. 1;and

Fig. 4 is a perspective view of the thread-tension-releasing device ofthe present invention, shown in detached state with thethread-tensioning means indicated diagrammatically in broken lines.

Referring now, in greater detail, to the accompanying drawings, the sameshow a sewing machine head, including a housing 10, for the actuatingmechanism of the needle and presser foot that is operated by a pulleywheel 12; individual tensioning means for three threads, two fed towardthe needle from the front of the machine, and one fed towards the needlefrom the table-facing end of the machine. The two tensioning means forthe frontfed threads are generally designated as 20 and 22, and haveassociated thread guides 24. The tensioning means on the work table endof the machine is generally designated as 26.

Each of the tensioning means 20, 22 and 26 consists of a first disc, 28,mounted in fixed position on a horizontally disposed shaft, 30, fittedon the housing 10, and an associated disc, 32, slidably mounted on saidshaft, and urged towards said fixed disc 28 by an abutting end of a coilspring 34, fitted about the shaft 30, whose other end may abut a knurlednut that is threaded on the shaft 30, for pressure adjustment. Each ofthe tensioning means discs 28 and 32 is formed with a peripheral flangethat flares diagonally outwardly away from that of the other, to providea groove, 35.

The device of the present invention is intended to simultaneouslyseparate and space the disc 32 of each of the thread-tensioning means20, 22 and 26, away from its associated fixed disc 28, so as to releasethe thread passing between the discs, for easy pulling out from themachine, for spacing the work, or similar purposes. The device comprisesa preferably U-shaped bracket having a base, 40, by which it may besecured to the top of the housing 10, and spaced, upstanding arms, 42and extending therefrom. .A lever, generally designated as 46, ispivotally mounted on one of the bracket arms,

as 44, by a pivot pin, 48. The lever 46 is preferably pivoted inoff-center position with its shorter arm, 50, which may be provided witha tapered bottom edge, 52, extending forwardly over and in alignmentwith the groove 35 of the tensioning means 26; the longer arm, :54, ofthe lever 46 counterbalancing the arm 50 to main- .tain the lever innormally elevated position above'such groove 35. Pivoted over the edgeof the other of the bracket arms 42, in transverse relation to the lever46, is a second lever, generally designated as, 56, which may be securedin place intermediate its ends by a hinge, 58, one leaf of, which issecured to the bracket arm 42 and the other secured to the lever 56. Onearm, 60, of the lever 56 extends in the direction of the lever 46 and isengaged thereby for simultaneous movement therewith, as by the hook, 63,formed onthe underside of its arm 54, which engages under the arm 60 ofthe lever 56. The ,other arm, 62, of the lever 56, is formed with aforked end each of whose tines, 64 and 66, is preferably formed withataperededge, 68 and 70, respectively, and extend, respectively, over thegrooves 35 of thread-tensioning means and 22. I I t The operation of thethread-tension releasing device of the invention will become apparentfrom the foregoing description. Normally the lever arm 50 and the tines64 and 66 are maintained in spaced position relative .to thethread-tensioning means 26, 20 and 22, respectively, by thecounterbalancingeffect of the longer lever arm 54, which may be ofsufiicient length and weight I9 the purpose to counter-balance its arm50, and at the same time press down upon the arm 60 of the lever v56.When it is desired to release tension on the threads passing through thetensioning means, the lever arm 54 is elevated by the operator. Thisdepresses the lever -arm 50 into the groove 35 of thread-tensioningmeans '26, to space its disc away from its disc 28, simultaneously thehook 62.0n the lever arm 56 elevates the .arm 60 of the lever56 todepress the tines 64 and 66, at the other end of the lever. 56, into thegrooves of the thread-tensioning means 20 and 22, respectively, to movetheir respective discs 30 away from the associated discs 28, to releasethe tension on the. threads passing between them. Release of lever arm54 will automatically return the device to normal, inoperative position.

This completes the description of. the device of the present. inventionand of the method of its operation. It will be readily apparent thatsuch device is of relatively simple and' economical construction; thatit may be readily modified with respect to shape and size, to besuitable for use on varioustypes of sewing machines having multiple,differently oriented thread-feeding and tensioning means; and that itmay be easily and conveniently installed on such machines. It will alsobe apparent that such device is easy, simple and convenient to operateand is certain and effective in its operation.

It will be further apparent'that numerous variations and modificationsinithe thread-tension releasing device of the present invention may bemade by anyone skilled in the art, in accordance with the principles ofthe invention hereinabove set forth, and without the exercise of 'anyinventive ingenuity. I desire, therefore, to be P iOtected for any andall such variations and modifications that may be made within the spiritof the invention and the scope of the claims hereto appended.

What ,I claim is: V

1., In combination with an overlock 'stitch or like sewing machine head,having a plurality of thread-tensionmg means, said tensioning "meanlocated on, 'd fie e sides of said sewing machine head, and eachcomprising a pair of parallel, vertically disposed, discs each having anedge portion flaring in a direction opposite to that of the other, toform a groove, and at least one of said discs being slidably mounted andspring-tensioned against the other, of means for releasing saidtensioning means comprising a first lever, meanspivotally mounting saidfirst lever intermediate its ends on said sewing machine head with onearm thereof overlapping the discs of a thread-tensioning means on oneside of said sewing machine head and in alignment with the groovebetween the fiared edges thereof, a second lever, means pivotallymounting said second lever intermediate its ends on said sewing machinehead with an arm thereof overlapping the discs of a spring-tensioningmeans on another side of said sewing machine head and in alignment withthe groove between the flared edges thereof, and means interengaging theother arm of said second lever with said first lever for simultaneousmovement into the I said grooves for spreading said discs away from oneanother upon the movement of the other arm of said first lever. 2. Thecombination of claim 1, wherein means are provided for normallymaintaining said first lever with its said first arm out of contact withits aligned groove. 3. The combination of claim 1, wherein said firstlever has its first named arm disposed above the tensioning means itoverlaps and hasits other arm ofrgreater weight than said first-namedarm thereof, whereby said first-named arm is o erbalanced to bemaintained out of contact with the groove aligned therewith. I

4. The combination of claim 1, wherein said secondnamed arm of saidsecond lever is interengaged with the second-named arm of said firstlever.

5. In combination with a sewing machine head having more than twothread-tensioning means disposed on two adjacent sides of said head andat least two ofsaid tensioning means being on the same side of saidhead, each of said tensioning means including a pair of parallel discsat least one of which is movable and is spring tensioned against theother, said discs each. having a flared marginal edge portion forminganannular channel with the edge portion of the other disc, of means forsimultaneously loosening said tensioningmeans comprising a first lever,means tiltably supporting said lever intermediate its ends on saidmachine head pointing to one of said sides on said machine head, asecond lever, means tiltably supporting said second lever intermediateits ends at an angle to said first lever, and pointing to the other ofsaid sides, the lever pointing to said side having the two tensioningmeans having a forked arm, said forked arm supported in position to haveits tines each overlapping one of the thread-tensioning means on saidside and aligned with the channel thereof, the other of said levershaving an arm overlapping the tensioning means on the other side of saidsewing machine head and aligned with the channel thereof, meansinterengaging said levers for simultaneous movement of their channelaligned ends toward and away from the contiguous aligned channel. I I II '6. The combination of claim 5, wherein said first lever and saidsecond lever are interengaged by the other of their arms. I

7. The combination of claim 5, including means for normally,automatically maintaining said aligned lever arms. in spaced relation totheir aligned channels.

8. The combination ofclaim 5, wherein one of said levers is supported inoverbalanced position, to normally maintain its aligned arm away fromthe contiguous tensioning means channel. 7

9. The combination of claim 5, wherein said levers are interengaged bythe other of their arms and one of said levers has its engaged armoverbalanced to maintainthe aligned arms of each of said levers awayfrom the associated aligned tensioning means. i s t '10-. in combinationwith'a sewing machine head having two thread-tensioning means on oneside thereof and 1 another thread-tensioning means on an adjacent sidethereof, each of said tensioning means comprising a pair of paralleldiscs supported on said sewing machine head, at least one of said discsof each pair being slidably spring-tensioned toward the other and eachdisc of each pair having its marginal edge portion outwardly flared toform a groove with the edge portion of the other, of means forsimultaneously spacing said discs from one another to relieve thetension, comprising a U-shaped bracket secured by its bight to the topof said sewing machine head, a lever arm pivoted intermediate its endson one of said bracket arms with one arm of said lever aligned with thegroove of the one tensioning means on one side of said sewing machinehead, a second lever pivotally supported intermediate its ends on theother of said bracket arms, said second lever having a forked end eachof whose tines is aligned with the groove of one of the tensioning meanson the other side of said sewing machine head, a slot formed in theother arm of said first lever, the other arm of said second leverengaged in said slot for simultaneous movement of the two levers intoand out of the grooves of said tensioning means for spacing andreleasing their discs from and toward one another, and means fornormally maintaining said levers with their disc-engaging ends out ofcontact with said discs.

11. The combination of claim 10, wherein said means for normallymaintaining said disc-engaging lever ends out of contact with said discscomprises an overbalanc- :0

ing weight on said other arm of said first lever.

12. A thread-tension releasing attachment for an over lock stitch sewingmachine head having thread-tensioning means on each of two adjacentsides thereof, said tensioning means each comprising a pair of paralleldiscs supported on said sewing machine head with at least one of saiddiscs movably mounted and spring-tensioned against the other, comprisinga substantially U-shaped bracket adapted to be secured by the bightthereof to the top of said sewing machine head, a first leverpivotallysupported intermediate its ends on one of the arms of the said bracketand a second lever pivotally supported intermediate its ends on theother of the arms of said bracket at substantially right angles to saidfirst lever, and means interengaging said lever for simultaneous tiltingin the same direction. 1

13. The attachment of claim 12, wherein each of said levers is formedwith a tensioning means contacting outer arm and are interengaged bytheir other arms.

14. The attachment of claim 12, wherein said second lever is formed witha forked outer arm, the tines of said arm each adapted to engage againstthe discs of a separate thread-tensioning means for spacing them apartand is engaged by its other arm on the said first lever.

References Cited in the file of this patent UNITED STATES PATENTS1,007,837 Almond Nov. 7, 1911 1,071,451 Moffatt Aug. 26, 1913 1,118,710Weis Nov. 24, 1914

